Lost circulation is a major problem that was often found in the well drilling process. This resulted in rock formations to become unstable, cause damage to wells, equipment, and workers. So to overcome this problem, drilling fluid will usually include lost circulation materials that act as connecting agents throughout the openings in rock formations, which physically close the formation of the opening by entering into the hole and prevent more fluid from coming out. The method used is laboratory research to test the rheology properties of sludge that has been treated with the addition of styrofoam (1 to 5 grams) under conditions of temperatures of 83 °F to 243 °F with intervals of temperature increase of 40 °F and testing using the Fann VG Meter. The measurement results are then compared with the standard. This test was carried out to see the effect of mass and temperature on the physical and rheological properties of drilling mud. The result of this research shows plastic viscosity, yield point, and gel strength of mud increases with increasing concentrations of styrofoam, and decreased when the temperature was increased. The combination of mud that best fits with the standard was addition with 1 gram of styrofoam.